Screen printing is used to form an electrode of a solar cell, and an electrode of a display such as a liquid crystal display, a plasma display, and an organic EL (electroluminescence) display. In screen printing, a printing mask, in which a part corresponding to an electrode to be printed on a printing object is a mesh (openings) and other parts are formed of a mesh filled with an emulsion, is arranged a predetermined distance apart from the printing object, and a paste containing an electrode material is provided to the printing mask. Thereafter, the paste is spread on the printing mask by a squeegee. The paste in only the mesh part out of the spread paste is provided onto the printing object. The paste provided onto the printing object is fired at a predetermined temperature according to the electrode material. Thereby, an electrode is formed.
As a printing mask used in screen printing, there has been conventionally proposed a printing mask prepared by coating a mesh with emulsion on the squeegee side surface, and thereafter, coating the mesh with emulsion on the surface to be opposed to a printing object. The emulsion is applied to the surface to be opposed to a printing object in a film thickness of 5 micrometers (hereinafter, “emulsion thickness”), and smoothness of the film is ensured (see, Patent Document 1).
Conventionally, at the time of applying paste on a printing object, an average film thickness of the paste applied from near the edge of the mesh part of a printing mask tends to be larger than that applied from the other parts. In order to solve the problem, there has been proposed a method of performing screen printing by using a printing mask that has a fine pattern with, for example, a U shape, a mountain shape, a wave shape, and a circle shape formed in the outline of a coating pattern, so that the amount of the paste pushed out from the printing mask decreases towards the end of the coating pattern (see, Patent Document 2).
Patent Document 1: Japanese Patent Application Laid-open No. H4-189545
Patent Document 2: Japanese Patent Application Laid-open No. H11-245534